The present invention relates to an optical disk device which reads data recorded upon an optical disk under servo control.
In the prior art, optical disk devices are generally widespread which, under servo control, irradiate laser light upon optical disks and read and replay data from the optical disks.
When an optical disk is loaded into this optical disk device, first, the optical disk device examines a first physical characteristic of that optical disk. The physical characteristic may be, for example, the reflectivity of the data recording surface of the optical disk to laser light, the wobble frequency of its data recording surface, or the rotational speed of a spindle motor when a constant voltage is applied to the spindle motor. Next, the optical disk device executes servo control based upon this first physical characteristic, and, under this servo control, reads type information which specifies the type of the optical disk. The type of the optical disk may be, for example, DVD-ROM, DVD-R, or DVD-RW. And the optical disk device makes a decision as to whether or not the first physical characteristic agrees with a second physical characteristic of the optical disk which is determined as being the standard for that type. Moreover, the optical disk device only starts reading replay data from the optical disk, if it has been decided that the first physical characteristic and the second physical characteristic agree with one another. Due to this, replay starts, and the user is able to view video and audio recorded upon the optical disk.
It should be understood that, in Japanese Laid-Open Patent Publication 2006-120225, there is proposed an optical disk device which decides whether or not the physical format information and the logical format information of an optical disk specify the same type of optical disk.
However, sometimes the type information described above is inaccurate due to a cause such as a recording failure of the data upon the optical disk, or the like. In this case, the first physical characteristic and the second physical characteristic do not agree with one another, and an optical disk device according to the prior art described above is not able to start reading out the replay data.
Thus, with an optical disk device according to the prior art described above, if the optical disk type information is not accurate, it has not been possible to replay that optical disk. Accordingly the user has been obliged to abandon his attempt to view the video and audio recorded upon the optical disk.
The objective of the present invention is to provide an optical disk device which can start reading replay data from an optical disk, even if the type information on the optical disk is inaccurate, and which is still capable of replaying the video and audio recorded upon the optical disk.